In existing public switched telephone networks (PSTN) that employ a signaling system 7 (SS7) architecture for call-setup, billing, routing, and information exchange, the number of the party placing a call is carried across the SS7 network between switches and between carriers. Customers may request a service that his/her name and number remain private, in which case the calling party number is still routed through the SS7 network but is also accompanied by a calling party restriction indicator (CPRI) which identifies that the calling party information is to remain private. When a call with a CPRI indicating the calling party information is to remain private is received at the last switch before a call is delivered to the end user, the calling party number is not delivered.
Government regulations impose a requirement that carriers honor privacy markings and not disclose information that has been marked private outside the network of recognized carriers, i.e. to end users and private concerns. Until recently, all SS7 switching equipment connected to PSTN networks has been owned by the PSTN carriers and not by private concerns. Accordingly, complying with government regulations has not presented a problem as existing SS7 systems removed the calling party information at the last switch, none of which were privately owned, and prior to delivery to the end user. This was sufficient to comply with the regulations.
Recently, however, private organizations have begun to install SS7 switching equipment of their own which is connected to public telephone networks. Where private switching equipment has been installed, the methods employed in existing SS7 networks would allow information that has been marked private to be delivered outside the network of recognized carriers to the privately owned switching equipment in violation of government regulations. SS7 networks simply were not designed to comply with the regulation where the last switch to which the called party is connected is privately owned.
Accordingly, there is a business need imposed by government regulations for systems and methods to insure that calling party information that has been marked private not be delivered to privately owned equipment, particularly in circumstances wherein a private organization owns the last switching point through which a call is routed.